Min Max Resolution

<!--
  说明：图层分辨率范围
  核心逻辑：用 minResolution / maxResolution 让两层在缩放时自动显隐
  依赖：OpenLayers 10.3.1 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>图层分辨率范围</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:10px;align-items:center;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar button{font:inherit;padding:4px 10px;border:1px solid #c9d0da;border-radius:5px;
              background:#fff;color:#1f2a37;cursor:pointer}
  #info{margin-left:auto}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <button id="zin">放大到 14</button>
  <button id="zout">缩小到 6</button>
  <span id="info">—</span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').innerHTML =
      '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var fromLonLat = ol.proj.fromLonLat;

  var points = [
    [116.30, 39.86], [116.36, 39.90], [116.42, 39.93],
    [116.46, 39.88], [116.39, 39.96], [116.34, 39.94]
  ];

  var features = points.map(function (p, i) {
    return new ol.Feature({
      geometry: new ol.geom.Point(fromLonLat(p)),
      name: '站点 ' + (i + 1)
    });
  });

  var source = new ol.source.Vector({ features: features });

  var detailLayer = new ol.layer.Vector({
    source: source,
    maxResolution: 20,
    style: new ol.style.Style({
      image: new ol.style.Circle({
        radius: 5,
        fill: new ol.style.Fill({ color: '#1f5fd0' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
      }),
      text: new ol.style.Text({
        text: '',
        font: '600 12px sans-serif',
        offsetY: -14,
        fill: new ol.style.Fill({ color: '#16181d' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 3 })
      })
    })
  });

  detailLayer.setStyle(function (feature) {
    return new ol.style.Style({
      image: new ol.style.Circle({
        radius: 5,
        fill: new ol.style.Fill({ color: '#1f5fd0' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
      }),
      text: new ol.style.Text({
        text: feature.get('name'),
        font: '600 12px sans-serif',
        offsetY: -14,
        fill: new ol.style.Fill({ color: '#16181d' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 3 })
      })
    });
  });

  var overviewLayer = new ol.layer.Vector({
    source: source,
    minResolution: 60,
    style: new ol.style.Style({
      image: new ol.style.Circle({
        radius: 9,
        fill: new ol.style.Fill({ color: 'rgba(226,110,40,0.85)' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
      })
    })
  });

  var view = new ol.View({ center: fromLonLat([116.39, 39.91]), zoom: 10, minZoom: 2, maxZoom: 19 });

  var map = new ol.Map({
    target: 'map',
    layers: [new ol.layer.Tile({ source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}) }), overviewLayer, detailLayer],
    view: view,
    controls: ol.control.defaults.defaults({ attribution: false, rotate: false })
  });

  var info = document.getElementById('info');

  function report() {
    var res = view.getResolution();
    var detailOn = res <= 20;
    var overviewOn = res >= 60;
    info.textContent = '分辨率 ' + res.toFixed(2) + ' m/px · 层级 ' +
      view.getZoom().toFixed(1) + ' · 细节层' + (detailOn ? '显示' : '隐藏') +
      ' · 汇总层' + (overviewOn ? '显示' : '隐藏');
  }

  document.getElementById('zin').addEventListener('click', function () {
    view.animate({ zoom: 14, duration: 500 });
  });
  document.getElementById('zout').addEventListener('click', function () {
    view.animate({ zoom: 6, duration: 500 });
  });

  view.on('change:resolution', report);
  report();
})();
</script>
</body>
</html>